A next generation multimedia wireless communication system that has been actively researched is required to process not only voices but also images, packet data and the like.
Orthogonal frequency division multiplexing (OFDM) scheme is a multi-carrier modulation scheme for transmitting data by using a plurality of orthogonal subcarriers and is one of core technologies that have been in the spotlight in the next-generation multimedia wireless communication system. Orthogonal frequency division multiple access (OFDMA) is a multiple access scheme by combining the OFDM with a frequency division multiple access (FDMA), time division multiple access (TDMA) or code division multiple access (CDMA).
In general, control signals are transmitted from a base station to a mobile station or from a mobile station to a base station periodically or event-drivenly. The control signal refers to a signal relates to decoding of traffic data, scheduling of traffic data and feedback of channel condition. Hereinafter, downlink refers to transmission from the base station to the mobile station and uplink refers to transmission from the mobile station to the base station. An example of the uplink control signals is a channel quality indicator (CQI). In general, the mobile station transmits the CQI to the base station periodically in order to report channel quality to the base station.
There are various kinds of uplink control signals. In order to provide various communication services, the control signals are needed to frequently be exchanged between the base station and the mobile station. The exchange of the control signals is called control signaling. Frequent control signaling between the base station and the mobile station may reduce capacity of system since control signaling does not contribute to the increase of data rate. Further, as the control signaling is increased, the lifespan of the battery, that is one of the major design restrictions of a mobile station, may be shortened.
A method is sought for minimizing overhead due to the control signaling so as to increase the capacity.